void main(List<String> args) {
  int n1 = 10;
  int n2 = 3;

  //加+
  print(n1 + n2); //13
  //减-
  print(n1 - n2); //7
  //乘*
  print(n1 * n2); //30
  //除 /
  print(n1 / n2); //3.....

  //取整：区出发结果的整数部分~/
  print(n1 ~/ n1); //3
  //取模：取除法结果的余数%
  print(n1 % n2);//1

   // 案例：计算购物车商品总价格：商品A一件，每件289.0元；商品B二件，每件39.0元
   double total=289.0 + (2 * 39.0);
   print(total); // 367.0

   // 解决办法：可以先把小数运算处理成整数运算
  double total3 = ((0.1 * 100) + (0.2 * 100)) / 100;
  print(total3);
}
